It is known that drawing-in comprises passing threads, obtained from the warp beam, through the wires of the warp stop, through the heddles of the heddle frames and through the dents of the reed. Given that the complete operation takes a considerable time, it is generally performed away from the loom, after which the beam thus prepared is transferred and loaded onto the loom. Automatic drawing-in is currently performed either with three separate machines, one for each of the three operations, in other words a wire setter, a heddle frame threader and a reed threader, or using a single machine for the three operations, simultaneously. The main machines of the second type as known today essentially has a group including the heddle hook, the heddle selector, the reed, the wire setter, the thread gripper, the magazines of the heddles and the wires; and a group comprising the warp beam support, the heddle frames, the warp stop and the leasing.
Drawing-in on such automatic machines entails manual intervention for the following operations.
Before drawing-in:
positioning of the warp beam the thread guards and the heddle frames on the support group;
positioning the leasing, aligning the leased threads with the beam, and fixing the threads thus aligned;
positioning the support thus prepared and latching into the control group;
positioning and selecting the reed. During drawing-in:
visual monitoring and manual displacement of the drawn in threads;
knotting of the threads after breaking. After the drawing-in:
unlatching the support group.
Following this, the beam, the warp stop, the reed and the square heddle frames are transferred by means of 30 carriages into the weaving room, where they are positioned on the loom. The operations require the intervention of specialized personnel, the use of special accessories, at least two support groups to avoid prolonged shutdown of the control group, and hence also a substantial availability of space. All these requirements mean that known automatic machines are very costly both in respect to their construction and in respect to their use. Only major industrial enterprises can employ them because continuous or virtually continuous use is necessary to justify economically profitable running thereof.